<!DOCTYPE html>
<html>
<head>
  <title>关灯</title>
  <meta charset="utf-8" />
  <link rel="icon" href="favicon.ico" />
   <meta name="viewport" content="width=device-width" />
</head>

<body>
<img id="pic" onclick="guanDeng()"
src="pic_bulboff.gif"/>
<script>
var i = 1;
function guanDeng(){
  if(i==1){
    pic.src = "pic_bulbon.gif";
    i=0;
}else{
   pic.src = "pic_bulboff.gif";
   i=1;
  }
}
</script>
</body>
</html>